It is known that, in a break-action gun, particular care must be taken in the formation of the aforementioned articulated connection between the barrels and the breech since the achievement of the desired smooth opening of the gun which has to be guaranteed over time depends to a large extent thereon.
For such opening, it is necessary to achieve the correct, calibrated friction between the components of the articulated connection with a continuing capability to take up both play of the assembly and the play which is inevitably created by the use of the gun.
A rod-shaped tensioning element (called a bracing element by experts in the art) is generally used for this purpose and is engaged releasably on the gun barrel by means of a lever which engages a hooked projection formed on or fixed to the barrel. The stability of the aforesaid engagement, and hence the functional capacity of the bracing element, is achieved with great difficulty by means of successive operations to correct the hooked projection.
The tension or "pull" between the barrel unit and the breech of the gun and the value of the friction necessary for the stability of the gun during opening depend on the dimensions of the rod-shaped element or bracing element (its length and/or thickness) . A satisfactory tensioning and stability can be achieved only by successive operations to correct and calibrate the rod-shaped element.
Precisely because the aforesaid multiple mechanical operations require skilled intervention and successive adjustments carried out manually at workshop level by skilled operators, the barrel/breech/bracing-element assembly of a break-action gun can be considered as a unique, highly individualized unit. For this reason, in a break-action gun, interchangeability of the barrel unit produced specifically for that gun with other barrel units of the same type is not possible unless all of the above-mentioned mechanical operations and skilled interventions are repeated.
The main object of the invention is to design a device which provides for mass-production interchangeability of the barrel unit of a break-action shotgun with other barrel units of the same type, overcoming the technical and economic problems currently involved by the manual and exclusive operations which up to now have been necessary for the individualized adaptation of a barrel unit to a respective breech.